How to Identify Simple Diodes

Last Updated: May 18, 2022

A diode is a simple electronic component which blocks current in one direction and allows it in the other. They can be manufactured to work forward or reverse, and with positive or negative voltage. Uses for a diode include, current protection, AC/DC conversion, and capture/emitting light. With so many varieties it can be difficult to determine what type a diode is.

Method 1

Method 1 of 2:

By Shape

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1
Look for legs on the side:
- 1. Standard Signal - This is the regular forward-biased diode.
- 2. Zener - Operated in reverse-biased to hold a constant voltage
- 3. Small Signal - Used for applications with a much smaller current but with much more accuracy
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2
Look for both legs under:
- 1. Light Emitting Diode - Emits a colored light based on the materials used internally
- 2. Photodiode - Captures photons to generate current
- 3. Infra-Red - Emits light at the infra-red spectrum
- 4. Varactor - A reverse-biased diode used as a capacitor
- 5. Schottky - Used for precision and when voltage needs to be conserved
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These will be chips in the form of a SMD (surface mounted device). To identify these you will need to look at the number.

Method 2

Method 2 of 2:

By Number

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Go to alldatasheet .
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Tips

If you cannot see number, it's best to throw it away and get a new one. Most diodes are cheap

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If your diode does not match anything shown, try the number search.

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If your diode is not listed on all datasheets, recheck the number to make sure you put in the correct one. Use a search engine to find other datasheet sites.

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Things You'll Need

Diode
Good light source (for seeing the numbers)
Device with internet connection

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How to Identify Simple Diodes

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